Measuring – text version

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When measuring the length of an object, first work out the units being used by your ruler or measuring tape.

Read the number of units on the largest mark to the left of the reading you are taking, then add on any sub-units.

For example, on a ruler marked in millimetres, a length that is 3 marks longer than 40 would be 43 millimetres long.

The next four diagrams show measuring the length of a pencil and a nail using a tape measure and a ruler. The tape measure uses millimetres (mm) on its scale and the ruler uses centimetres (cm).

Tape measure showing the length of a pencil.

In the above diagram the length of a pencil is shown on the tape measure as 135 mm. On the scale of the tape measure the first major unit that is less than the length of the pencil, is 100. The next sub-unit that is shorter than the length of the pencil is 30. From the 30 to the end of the pencil there are five minor divisions. The length of the pencil is therefore 100 mm plus 30 mm plus 5 mm which equals 135 mm.

Tape measure showing the length of a nail.

In the above diagram the length of a nail is shown on the tape measure as 65 mm. On the scale of the tape measure the nail is shorter than any of the major divisions, it is shorter than the 100 mark. The sub-unit that is shorter than the length of the nail is 60. From the 60 to the end of the nail there are five minor divisions. The length of the nail is therefore 60 mm plus 5 mm which equals 65 mm.

Ruler showing the length of a pencil.

In the above diagram the length of a pencil is shown on the ruler as 13.4 cm. The first major unit, less than the length of the pencil, is 13. From the 13 to the end of the pencil there are four minor divisions, that is zero point four. The length of the pencil is therefore 13 cm plus 0.4 cm which equals 13.4 cm.

Ruler showing the length of a nail.

In the above diagram the length of a nail is shown on the ruler as 6.5 cm. The first major unit, less than the length of the pencil, is 6. From the 6 to the end of the nail there are five minor divisions, that is zero point five. The length of the nail is therefore 6 cm plus 0.5 cm which equals 6.5 cm.

Do it

For each of the following questions choose correct answer from the list provided.

Question 1

Using a tape measure with millimetre scale you have to measure a piece of timber for cutting at 828 mm. Which of the following methods is correct for reading the scale and putting together the total measurement?

  1. 800 plus 30 plus 2
  2. 800 plus 25 plus 3
  3. 800 plus 20 plus 8
  4. 800 plus 10 plus 8

Question 2

Using a tape measure with millimetre scale you have to measure a piece of timber for cutting at 780 mm. Which of the following methods is correct for reading the scale and putting together the total measurement?

  1. 700 plus 80 plus 0
  2. 700 plus 70 plus 10
  3. 700 plus 90 plus 0
  4. 700 plus 80 plus 5

Question 3

Using a tape measure with millimetre scale you have to measure a piece of timber for cutting at 389 mm. Which of the following methods is correct for reading the scale and putting together the total measurement?

  1. 300 plus 80 plus 2
  2. 300 plus 80 plus 9
  3. 300 plus 90 plus 1
  4. 200 plus 80 plus 9

Question 4

Using a ruler with centimetre scale you have to measure a piece of timber for cutting at 19.4 cm. Which of the following methods is correct for reading the scale and putting together the total measurement?

  1. 19 plus 0.5
  2. 19 plus 0.6
  3. 19 plus 0.9
  4. 19 plus 0.4

Question 5

A piece of timber is 757 mm long. How long is this in metres?

  1. 0.757 m
  2. 7.57 m
  3. 75.7 m
  4. 757 m

Question 6

A piece of timber is 80.6 cm long. How long is this in metres?

  1. 80.6 m
  2. 806 m
  3. 8.06 m
  4. 0.806 m